Sks slam fire issue... But probably not what you'd expect!

[bhhacker]

Hi guys. A buddy of mine bought an Sks in *barf* bullpup configuration. All bad taste judgements on that side.... Here's the story...


He goes to the range and it's sometimes dumps the mag full auto, sometimes just does 3 or 4 or 5 round bursts. He s telling me in passing that he doesn't feel safe taking it to the range anymore because who knows what it will do.

So I've been around the block a time of two, and the block has been around me the same so tell him to bring the bolt over because I'm sure the free closing on is probably stuck in there pretty bad.

He brings it over and the thing looks cleaner than my Romanian Sks and the bolt pin is rattling quite freely. Well... Crop. I bresk it down, boil it, and not that huge amount of cosmo scum coming out. Juuuuust enough to get yelled at by the missus for ruining one of her pots. DOH!


Its been sitting in mineral spirits overnight. My question is this... If this doesn't fix it, which it always has, but the pin has in previous experiences super gunned in cosmo, what's the next step?


A new shear? He wants to buy. That Murray bolt, but if it's not the bolt, that won't fix it. What do you guys think?

I'd also like to add that we live in Juneau Alaska and have no local gunsmith, so we CAN send it out, but if it's fixable here it would be less of a pain in the butt to ship out for something simple like a 10 dollar part...plus shipping, plus the smith fees.


What you guys think?


P. S. Really makes my heart hurt to ask a question like this with RC gone because you know he would have had some crazy awesome fix using bubblegum and duct tape and could have laughed with me about it. RIP friend

 

[Shaq]

What type of ammo is he using? The SKS is designed for military ammo which has harder primers than regular factory ammo to prevent slam firing. Whenever I chamber a round in my SKS, then extract the round, there is always a light firing pin dent on the primer.

 

[kBob]

Hmmmm, bullpup you say. I wonder if the necessarily long extentision between the stock's trigger and the trigger of the actual SKS might be enough weight to cause something like bump firing to be going on.

can you fit his rifles Barrel and receiver group and trigger mech in your stock and see if it does the same?

Of course there is always the chance that the previous owner WANTED it to fire bursts and did "something"

I miss RC as well.......what am I going to do with all this bubble gum and duck tape?

-kBob

 

[RUT]

https://murraysguns.com/sks-firing-pins/

 

[Telekinesis]

It could be something with the bulpup configuration, so maybe see if you can put it back in a normal stock and see if that's the culprit. I don't think this is the answer, but you never know.

While you're there with everything in pieces, check that the trigger group functions correctly. The SKS is one of those guns that the "home dremel expert" loves to tinker with.

Assuming the bolt/firing pin channel is ok, I wouldn't expect it to be the culprit unless you're using extremely sensitive primers.

 

[bhhacker]

Well the thing is, his pin floats, it's not stuck at all. My next plan of attack after putting his pristine bolt back together. (barely any carbon... Let alone cosmo in there) is to drop it into my Sks and see if it works, then drop my bolt into his bull pup.

I have a sneaky suspicion that Bubba before him that put that bullpup in there wanted it to be like this so that's where I'm at right now.


Mine is Romanian, his is Chinese. We both shoot that superb great wolf and Tula Ammon so that soft primer issue shouldn't be a problem either.

 

[LoonWulf]

yeah, i think your on the right track that may have been Induced, tho not necessarily intentional.
Id pull the gun apart and go over all the firing components. It could be a simple as a poor trigger job, or worn parts.

 

[ColoradoMinuteMan]

I'm with everyone else on, who knows what has been done to the trigger group. That is a good place to start. One other place to looks is at the bolt face. Things like dry firing can cause that the firing pin to flare the firing pin hole on the bolt face causing it to protrude just enough to cause a slam fire, or causing the firing pin to hang up on the lip just long enough to cause a slam fire. You may want to take a look at that.

 

[guyfromohio]

I had one in 1997. Went full-auto on me as well. Took it to the gun shop and they gave me $60 for parts. Never did figure out what was wrong.

 

[adcoch1]

Look at the bottom of the hammer. It should have a little cam type lobe on the bottom. If thats gone, a new hammer is in order. Next check the trigger disconnect down in the front bottom of the frame. There is a hole to witness the engagement. Make sure to hold the hammer while checking this so it doesn't whack your finger, it REALLY hurts if it gets ya.

 

[Steel Horse Rider]

Murray is the solution whether you have the full auto problem or not. All my SKS's have gotten the Murray treatment, I think the spring is the thing.....

 

[boom boom]

Sks boards has some pretty shrewd characters. If it was stock, the Murray fix mentioned above should fix it. But a bullpup kit plus potential bubba trigger work introduce s some new variables. Btw, I reload for the sks and use regular primers with the Murray firing pin fix.. no slamfires.

 

[highpower]

Since the bolt was clean when you took it apart, I doubt very much if that is what was causing the problem. I would drop the action into an original stock and try it that way. If it still goes straight into rock&roll mode, change out the trigger group. That way you can isolate the problem without jumping through a bunch of hoops. Since it doesn't always empty the magazine every time, I suspect it is either something to do with the bullpup trigger or the previous owner screwed with it so it would go all Rambo.

 

[Sunray]

"...sometimes dumps the mag full auto..." Indicates something odd with the sear. The sear may be worn, broken or a previous owner fiddled with the trigger. A visual inspection will show tool marks if the latter happened. However, sometimes it can be the ammo alone. If he's using light reloads, that can do it. Know a guy who had a semi'd Uzi that'd Rock and Roll with cast bullet loads.
That bull pup stock may be the whole cause though. It's fit is important and some times will interfere with the trigger group.
Anyway, Gunparts wants $20.50 for a sear. Sold out of $19.60 hammers.

 

[HJ857]

It's been a long time since I messed with an SKS. I seem to recall that it is possible to install the firing pin incorrectly.

Does the pin fully retract if you push it in with your finger, or is there a small amount that still extends from the bolt face? If so, disassemble, rotate the pin 90 or 180 degrees, insert the retainer and test it.

The Murray pin will not necessarily fix your problem. The spring on that pin can degrade fast and cause more slamfires than a normal firing pin.

 

[Steel Horse Rider]

I have neither experienced nor heard of that particular story. Do you have specifics about Murray springs degrading quickly?

 

[ColoradoMinuteMan]

I have neither experienced nor heard of that particular story. Do you have specifics about Murray springs degrading quickly?

The was a period of time when Murray's had some issues with firing pins. They were upfront about it when it occurred and I believe they attributed it to their heat treating vendor. A small number of them broke and jammed and cause a slam fire but it was pretty limited by the sound of it. If you google "Murray's broken firing pin" you will find more information. That was a number of years ago now, and haven't heard of an occurrence in several years. Murray's is stand up company that makes quality products. I've never had a slam fire with a clean bolt and firing pin, but some swear by the spring loaded pin.